Research On The Warm Asphalt Binders Modified By Polyphosphoric Acid

Currently, warm asphalt binder was being gradually attention, because of its good road performance and energy saving effect. However, compared with HMA, its performance still lags far behind needs further modified. In warm asphalt binder mixing polymer modifier has achieved initial success, but polymer modifiers higher cost than acid(polyphosphoric acid) modifier and polymer modifiers, and acid modifier and polymer modifiers has good modification effect in the high temperature stability of asphalt and aggregates to improve the adhesion and asphalt mixture. The example of mixing in warm asphalt binder polyphosphoric acid not yet appeared in domestic.This article uses two warm mix agents(Sasobit and Evotherm-DAT) composite with polyphosphoric acid separately. Preparation of WMA and four kinds of PPA content of warm asphalt binder(0.5%?1.0%?1.5%?2.0%). Study the base asphalt, warm asphalt binder and modified warm asphalt binder in terms of conventional performance, aging performance and high(low) temperature performance. In this study analyses the temperature mixing mechanism and modifying mechanism and the interaction mechanism of asphalt by fluorescent microscope, infrared spectra and thermo gravimetry-differential scanning calorimetry.(1) Both Sasobit and DAT have impaction on the conventional performance of asphalt, high temperature deformation resistance and elastic properties of asphalt were enhanced after the addition of those two warm mix agents. Short-term aging and long-term aging resistance ability were improved. The modification effect of Sasobit is superior to that of DAT. The low temperature performance of asphalt was weakening after adding those two warm mix agents.(2) The deformation resistance and high temperature performance of warm asphalt binder was improved significantly after PPA was added. The sensitivity to temperature and load frequency of PPA modified warm asphalt binder was decreased. PPA modification improved the short-term aging and long-term aging resistance ability of warm asphalt binder. What's more, in order to meet the requirement of the standard, in which stiffness modulus should be not more than 300 MPa and the creep slope should be not less than 0.3, the recommend content of PPA in Sasobit warm asphalt binder and DAT warm asphalt binder should be no more than 1.0% and 1.5%, respectively.(3) Sasobit and DAT have good compatibility in base asphalt. PPA fine and uniform distribution of the particles in DAT warm asphalt binder and warm asphalt binder compatibility with PPA and warm asphalt binder relatively stabilized when PPA content was 1.0% and 1.5%. Because of Sasobit and DAT incorporation content led to a change of four components in asphalt binder, and added PPA result two warm asphalt binder phosphorylation reaction of long-chain hydrocarbon molecules components, resulting in certain degree asphalt hardens. So incorporation of PPA can increase the high temperature performance of asphalt, Sasobit effect of improving the thermal stability of asphalt better than DAT, PPA is incorporated makes the two warm asphalt binders thermal stability has been significantly improved by analyses of thermo gravimetry-differential scanning calorimetry.